US 3040458 A
Description (OCR text may contain errors)
June 26, 1962 c, MATHEWS 3,040,458
ILLUMINATED COUNTER Filed Oct. 14, 1960 g C IINVENTOR.
BY C5 2 ATTOk/E United States atent C 3,040,458 ILLUMINATED COUNTER Edward C. Mathews, Flushing, N.Y., assignor to Simmonds Precision Products, Inc., Tarrytown, N.Y., a corporation of New York Filed Oct. 14, 1960, Ser. No. 62,777 Claims. (CI. 40-77) The invention relates to improvements in integral lighting and, more particularly, to the lighting of counter wheels by encompassing them with a transparent sleeve, the inner surface of which has indicia suitably applied thereto by my method set out in United States patent application Serial No. 154,310, filed November 22, 1961.
The theory of light piping through highly refractive media by virtue of total internal reflection of light rays, making greater than a critical angle of incidence with the walls of the medium, is well-known in the art. However, up to the present time this method has had the inherent disadvantage that it is impossible for such light to enter the medium through one of the surfaces by Which light is internally reflected. Heretofore, such devices have always had the light introduced through an edge of some auxiliary surface other than those which confine the light.
Accordingly, the principal object of the invention is to provide a counter wheel or other indicia bearing medium in which light enters the outer walls of the transparent sleeve in such a way that it makes almost critical angles of incidence with the wall of the sleeve on internal reflection.
Another object of the invention is the elimination of bright spots which normally occur in the presently used devices due to the placement of the light source.
A still further object of the invention is to provide an arrangement readily adaptable to a standard type counter with very lit-tie modification.
Still another object of the invention is to provide a lighted indicia bearing medium of simplified construction which will give superior results.
A still further object of the invention is to provide a lighted counter which gives substantially uniform illumination as well as high contrast between the numerals and the supporting background.
Another advantage of this invention is to provide a lighted counter which gives even uniform illumination,
less glare and high contrast between the numerals or other indicia and the background.
In the accompanying drawing illustrating the invention, in the several figures of which like parts are similarly designated:
FIGURE 1 is a cross sectional view of the counter wheel illustrating the invention.
FIGURE 2 is a perspective view of the invention.
Referring now to the drawing for a more detailed description of the invention and more particularly to FIG- URE 1 there is shown a counter wheel upon which is in serted a transparent ring 2. This ring can be made of any transparent material such as plastic, glass, or some similar material. The counter wheel 4 is usually of opaque material such as metal, nylon, etc. and is of standard manufacture and can be readily obtained from a number of sources.
It is not practical to introduce the light through the edge of a counter wheel enveloped by a light piping medium. In this applicants concept, the illumination depends on light which enters the outer walls of the glass cylinders in such a way that it makes almost critical angles of incidence with the walls of the cylinder on internal reflection. The path of a typical light beam is shown in FIG. 1. The light rays entering the counter by making small angles with the tangent of the counter re- Patented June 26, 1962 sults in that portion of the light which enters by refraction having nearly critical angles of incidence on subsequent reflections. The optimum path by which light travels from the light source to the indicia depends upon two phenomena. One, the efficiency with which the light initially enters by refraction and two, the efliciency with which the light is reflected on subsequent multiple reflections. The first phenomenon has its greatest efliciency when the light approaches the refractive medium perpendicularly. This, however, results in angles of incidence within the refraction medium which give very low efficiencies of internal reflection. Conversely when the ray approaching this refraction medium does so making a very small angle with the tangent, the efiiciency of initial transmission is poor, but subsequent internal reflections occur at nearly their critical angles and therefore have high efliciency. A compromise between these two extreme conditions is therefore required. Since, however, the initial transmission of light occurs only once and the subsequent internal reflections occur very many times in normal configurations, the compromise must favor the condition in which a large loss is accepted at the initial transmission thereby giving high efliciencies in the often recurring internal reflections. For this reason, this invention requires light approaching at an angle close to the tangent to the surface of the counter.
It is to be understood that the remaining rays are not being blocked out as these rays do not detract from the operation of the invention. However, the excellent illumination that is realized is due to the rays which enter as described above.
The viewing mask, indicated at 1, is positioned in close proximity with the counter wheel 4, but not in intimate contact therewith. Illumination of the indicia 3 carried by wheel 4 is indirectly supplied by lighted bulb 5. It is to be noted that light source 5 can be in any position as long as it is behind mask 1 and in line with counter wheel 4. The numerals or indicia 3 are applied on the inside of the transparent ring 2 by any suitable process. The light rays entering the transparent ring 2 at an angle from light source 5 are retained in the transparent ring 2, as shown in FIGURE 1, and are reflected outward from the numerals or indicia 3 at the display window provided in the mask 1. Therefore, it can be seen that only the numerals or indicia 3 are illuminated as they revolve past the opening in the mask 1. There can be no wetting of the interface between transparent ring 2 and counter wheel 4. Any substance that wets the interface causes light to be absorbed from the wetted area resulting in reduced illumination of the numerals or indicia 3.
Referring now to FIGURE 2 there is shown a three dimensional view of the transparent ring 2, on which inner surface numerals or indicia 3 have been placed. A certain relative size is illustrated for the transparent ring 2. It is to be understood that transparent ring 2 can vary in thickness, width and diameter according to the size of the counter wheel 4 which is shown in FIGURE 1.
It is to be understood that the present invention is not to be limited to counter wheels but is applicable to any curved surface or wheel such as a flexible transparent tape.
Although a single embodiment of the present invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of the parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.
What is claimed is:
1. A device of the type described comprising a drum provided with an opaque periphery, a transparent ring encompassing said periphery, indicia applied to the inner surface of said ring, a light source spaced from the periphery of said transparent ring for supplying light rays to provide illumination of said transparent ring, said light rays making small angles with the tangent of said ring whereupon that portion of the light which enters by refraction has nearly critical angles of incidence on subsequent reflection.
2. A device of the type described in claim 1, wherein an opaque surface provided with a viewing aperture is positioned in close proximity to the transparent sleeve, said viewing aperture being arranged to permit seriatim observation of said indicia.
3. An illuminated counter comprising an opaque drum around which drum a transparent sleeve is encompassed, indicia applied to the inner surface of said transparent sleeve and a light source positioned along the periphery of said transparent sleeve for supplying light rays to provide illumination of said transparent sleeve, said light rays making small angles with the tangent of the sleeve whereupon that portion of the light which enters by refraction has nearly critical angles of incidence on subsequent reflection.
4. A device of the type described comprising a drum provided with an opaque perimeter, a transparent sleeve supported by said drum, indicia applied to the inner surface of said transparent sleeve and a light source disposed exteriorly of said sleeve and serving to direct a beam of light upon the perimeter of said sleeve to illumine the indicia carried thereby.
5. In indicator means, a support member, transparent sleeve means carried exteriorly of said support member, said sleeve means being provided at its surface adjacent to said support member with legible indicia and means to direct a beam of light upon said sleeve means from a source exterior thereto.
References Cited in the file of this patent UNITED STATES PATENTS 1,648,977 Weidner Nov. 15, 1927 1,696,489 Kahn Dec. 25, 1928 2,159,095 Madan May 23, 1939 2,259,910 Rylsky Oct. 21, 1941 2,499,824 Haecker Mar. 7, 1950 2,640,144 Levy May 26, 1953 2,737,744 Sturges Mar. 13, 1956 2,795,878 Welland June 18, 1957